Current examples of healing caps are exemplified by U.S. Pat. Nos. 4,856,994, 5,006,069, 5,030,096, 5,035,619, and 5,154,612. 4,856,994 shows an implant installed in a jaw bone. The implant has an internally threaded bore that opens to the gum and an hexagonal fitting placed on top of the implant. An opening in the gum is preserved by use of a healing cap having an upper convex surface. The cap is intended to be flush or slightly outside the outer surface of the surrounding gum. The underside of the cap is reentrantly shaped to provide a cavity surrounded by an annular skirt terminating in an annular meeting surface. The cap is installed on the implant by threading a post into the threaded base of the implant until the annular meeting surface is in contact with the top surface of the implant. The novelty of this invention is to shield the upper surface of the implant from overgrowth of gum tissue and at the same time maintaining an opening through the gum tissue that overlies the implant. An additional feature is the use of a manipulating tool that fits into the cap and enables it to be fixed and located in place. U.S. Pat. No. 5,006,069 pertains to fixing a temporary restoration to an underlying implant. A dental coping is in the form of an elongated tubular body and has a base portion that is adapted to the first end of the body to mate with a support in the form of an integrated tapered post component that has a transmucosal section and a conical supragingivally extending male post section. A thin walled portion of the body extends upwardly from the base portion and has a seat for a bolt that fixes the tubular body and tapered post to the implant. The coping is intended for removably fixing a temporary restoration on the support. U.S. Pat. No. 5,030,096 has to do with an implant healing cap and holder. The invention enables a surgeon to handle an implant within the patient's mouth more readily. A threaded screw cap fits into a biocompatible implant. The cap screw has a head about the diameter of the end of the implant to protect the same. There is a cavity in the head of the cap for insertion of a wrench. A holder has a projection that fits resiliently into the cavity of the screw cap. After the installation of the implant with a screw cap by gripping the holder, positioning the implant and pushing it into place, the holder can be simply removed by bending the holder to one side and removing the holding projection from the cavity. U.S. Pat. No. 5,035,619 teaches a dental implant that has improved resistance to infection and a healing cap that does not need to be removed upon installation of a temporary or permanent crown. The invention uses a cover screw for sealing the hollow portion of the implant fixture during the time the jaw bone is growing about the fixture. After osseointegration of the fixture, the gingiva is reopened, the cover screw removed and replaced by a transmucosal healing cap. The healing cap is configured to allow the gingival tissues that were surgically displaced during removal of the cover screw to heal around the cap in a shape that is dimensionally similar to the previously removed tooth. The healing cap is made in two parts, one part being of frustoconical shape and having a stem attached to its proximal end and a cylindrical part above the frustoconical part that has a screw head segment for insertion of a driving tool. The fixture has a raised lip at its upper surface which may be circular or hexagonal. The lip fits within an approximately configured socket of the healing cap and its engagement within the socket provides additional support to the securing of the healing cap to the fixture. Several other types of healing caps are shown. After healing, the cap is removed and replaced by an abutment having an emergence profile matching that of the healing cap. U.S. Pat. No. 5,154,612 shows a device which includes a dental implant having a titanium screw and a spacer element arranged between two natural teeth. A crown between two natural teeth is applied on the spacer by means of cement. Prior to placement of the crown a cap is temporarily arranged on the spacer during which period the gum swelling will subside. The base part of the cap is wider than the base part of the spacer in order to hold the gum away from the shoulder of the spacer element and a pocket can be formed in the gum that is slightly larger than the crown. The base part of the cap extends some distance down into the edge of the gum.
The patents cited above show the state of the art. To recapitulate, the dental implant is generally performed by an oral surgeon. After a healing period of 3-6 months, the implant is exposed. A general dentist or prosthodontist then performs the restoration, which involves placement of an abutment of a specific size and shape over the fixture and securing the same by means of a bolt threaded into a cavity in the fixture. The implant fixture distal surface contains a flat, polished outer ledge and a central hex which is then engaged by a tool during placement. Also indicated by the prior art is a submucosal healing cap and a transmucosal healing cap to prevent the anatomy from becoming infiltrated with tissue from the gingiva and/or bone. The removal of such tissue is difficult and causes scratching of the abutment. In addition to keeping tissue out of the fixture the healing cap establishes a sulcus or opening above the fixture to allow placement of an abutment. The sulcus formed by the healing cap must be of sufficient size so that the various permanent abutments fit comfortably without causing tissue tearing and bleeding.
While these aforementioned healing caps have done a credible job in preventing tissue infiltration and establishing the necessary profiling for abutment attachment and placement of a tooth analogue, they suffer from a common defect in that while they screw into place using the fixture's internal threaded channel, they tend to loosen in a high percentage of cases, regardless of the torque used to tighten them. The result is tissue infiltration over the distal surface of the fixture. Removal of this tissue must be attempted under local anaesthetic. Such removal is difficult, uncertain, painful and likely to cause highly undesirable scratching of the highly polished surface of the fixture. Furthermore, because of the excessive torque sometimes used to tighten the healing cap on the fixture, breakage of the fixture and/or the healing cap can occur. Finally the high torque used to loosen the healing cap may loosen the fixture as well, causing damage to the osseointegration between the bone and fixture. Thus there exists a need for a healing cap that can obviate the above mentioned difficulties.
It is an object of this invention to design a healing cap and lockwasher that will not loosen and thus avoid tissue infiltration on the surface of the fixture.
It is a further object of the invention to prevent the need for removal of tissue that infiltrates the distal surface of the fixture.
It is still an object of this invention to design a healing cap that will avoid the use of excessive force when affixing to the implant so as to prevent damage to the fixture or healing cap or both.